1. Field of the Invention
The present invention relates to a technique for reading an original placed on a reading plate.
2. Description of the Related Art
In recent years, a reading apparatus has been developed that reads an original placed on a document positioning plate (reading plate) while facing upward, with an imaging unit mounted above the document positioning plate. With some techniques available in the processing described above, an appropriate timing for image capturing is automatically determined according to the state of the document positioning plate. Thus, a user no longer needs to set the specific reading timing.
Japanese Patent Application Laid-Open No. 9-307712 discusses a technique of using a distance measurement unit, such as a range sensor, to determine that a page of an original is flipped based on the change in the distance to the original, and executing the reading every time the page is flipped.
A document camera discussed in Japanese Patent Application Laid-Open No. 2000-4390 includes a motion detection unit for detecting a video signal on the document positioning plate. A still image, captured when a motionless state on the document positioning plate continues for a predetermined period of time, is output to a video projector. Thus, a document used for presentation is displayed as a real time image, and visually undesirable operations such as changing of the document is not displayed.
In the reading apparatus, in which the original is placed on the document positioning plate while facing upward, a single original, as a reading target, can be easily formed by disposing a plurality of originals one on top of the other or side by side as desired. However, when the originals are moved in such a manner, the same operation with the same change in distance, such as “page flipping”, is not necessarily repeated. Thus, the determination to execute the reading, every time the same operation is repeated, as in Japanese Patent Application Laid-Open No. 9-307712, cannot be performed in such a case. When the image is captured (reading is executed) at a timing where the space on the document positioning plate stay motionless as in Japanese Patent Application Laid-Open No. 2000-4390, every time the motion on the document positioning plate stops, in a process of disposing a plurality of originals one on top of the other or side by side as desired, the still image representing each motionless state is captured. When a large amount of resultant images of the incomplete states are stored, the user, who only wants the reading to be executed for the completed original, needs to go through a cumbersome procedure of selecting and deleting images.